How do I find Old Sherman's?

Hint 1 of 6:

You need to look for some evidence against the taxidermist.

Hint 2 of 6:

He's probably the murderer.  Can you find something to prove it?

Hint 3 of 6:

The scalpel will provide that information.  Talk to Watson to confirm your
opinion.

Hint 4 of 6:

Now all you need to do is track him down.

Hint 5 of 6:

If it helps you, Old Sherman owns a dog that can track a scent.

Hint 6 of 6:

Can you find something that might have Blackwood's scent?